Ambient occlusion (AO) is a technique used to calculate how exposed each point in
a scene
is to ambient lighting. The lighting at each point is a function of other geometry
in the
scene. For example, the interior of a building is more occluded and thus appears darker
than
the outside of the building that is more exposed.

Lumberyard uses height map-based ambient occlusion (AO), which is a high-performance
and
efficient method of providing ambient occlusion in outdoor environments without the
need for
prebaking. This make it suitable for PC, consoles, and virtual reality headsets.

In the Rollup Bar, click the Terrain tab, and then
choose Environment.

Under Terrain, select the Height map AO check
box.

The influence that height map AO provides can be restricted using clip volumes and
vis
areas. Both of these object types have a IgnoreHeightMap AO check box
that will locally disable height map AO inside the volume or area.

By default, evaluation is performed at quarter-display resolution. This can be changed
using the r_HeightMapAO console variable, as listed below.